Vacuum regulation.



H. C. SNOOK & E. W. KELLY.

VACUUM REGULATION.

APPLICATION FILED JUNE n, 1915,

Patented Nov. 20, 1917.

3 SHEETS-SHEET l.

HL C. SNOOK I E. W. KELLY.A

VACUUM REGULATION.

APPLICATION FILED IuNE II. I9I5.

H. C. SNOOK & E. W. KELLY.

VACUUM REGULATION.

APPLICATION man JUNE l1, |915.

1 ,$47,027. Patented Nov. 20, 1917.

3 SHEETS-SHEET 3.

KOMEN CLYDE SNOOK, OF GYN W Yy D, AND EDWIN W. KELLY 01E' PHIL xiiiPENNSYLVANIA.

VACUUM REGULATION.

igaiaoav.

Continuation of application Serial No. 848,708, led July 3,V1914.` `Thisapplication filed June 11, 1915. Serial 110.153.433.

To all whom t may concern.'

Be it known that we, HOMER CLYDE SNooK and EDWIN W. KELLY, citizens ofthe United States, of Cynwyd and'Phladelphia,

State of Pennsylvania, have invented new and useful Improvements inVacuum Regulations, of which the following is a specification.

Our invention relates to means for regulating the degree of vacuum of anX-ray tube or other vacuum tube.

Our invention resides in means for changing the vacuum of an X-raytube'or other,

vacuum tube comprising an osmotic member a part of which is thick ormassive for purposes hereinafter described; our invention resides inan'osmotic regulator for both raising and lowering the vacuum by meansof a single osmotic member or membrane ourinvention resides in anosmotic regulator in which the regulating gas to be admitted to thevacuum through the osmotic member is liberated or produced as and whenrequired either by electrolysis, dissociation or otherwise; ourinvention resides also in a regulating system involving the use of anosmotic membrane or osmotic membranes in combination with certaincircuit connections and arrangements and auxiliary apparatus.

Our invention resides in the structures and apparatus hereinafterclaimed. A

This application is in part a division and continuation ofourapplication Serial Number 848,708, upon which has been granted PatentNo. 1,143,327, June 15, 1915.

For an illustration of some lof the forms our invention may take,reference is to be had in the accompanying drawings, in which:

Figure 1 is a longitudinal sectional view through an X-ray tube and itsregulators.

Fig. 2 is a horizontal sectional view through the regulators of Fig. 1with the circuit connections slightly altered.

Fig. 3 is a diagrammatic view of circuit arrangements suitable for thepractice of our invention.

F ig. 4 is a sectional View through regu-i lators with a diagrammatic'illustration of means for heating the osmotic members.

Fig. 5 is a sectional view through a vacuum raising and loweringregulator by which regulating gas may be produced electrolytically.

Fig. 6 is a sectional view through a vacu- "um raising and loweringregulator in which .tials.

Fig. 11 illustrates a modied form of osmotlc tube or member suitableAfor use in connection with a spark gap.

' Referring to the drawings, B is the usual bulb of'an X-ray tube havingthe glass anode stem D and the glass ycathode stem E. Within the tubeare the usual anode or target or anticathode A and the cathode C. j Inthe example illustrated the head 1of copper or other suitable materialis'secured to the metallic tube 2, as of steel, whichkflts over thetubular glass stem 3 joinedto the stem D at 4. A tube 5,y of copper orvother suitable material, is set into the head-Il .and preferably weldedthereto forming aigacuum tight joint.v The tube 5 extendsv through thestem. D and at its end is welded ory soldered at a vacuum tight joint tothe platinum or othertube 6 which is sealed into the end of the glassstem D forming a vacuum tight joint. A corrugation 6a in the tube 6yields, under expansion and contraction of the tube 5 due' totemperature changes, and therebj.T prevents breakagel of seal betweentube 6 and glass stem D. Within the tube 5 is disposed a metallic tube 7which at its inner end has anysuitable metallic projection 8 formingelectrical contact with the tube 5 or head 1. Near its outer end thetube 7 is connected, as by soldering or brazing, to the metallic ferrule9'embracing the end of the glass stem D. Electrical connection is maderom the positive terminal of a suitable high tension source of currentwith the ferrule 9 or the tube 7. The eXtreme end of the rammed Nomea,iai a.. l

tube 7 is connected by rubber hose or otherwise with a supply of anysuitable 'cooling medium, for example a supply of air under pressure, ortoy a. suction' pump or partial Vacuum.

Accordingly the air will pass into and through the tube 7, strike thehead 1, from which the tube 7 is suitably spaced, extracting heat fromthe head1 which conducts the heat away from the target proper, the

air then passing loutwardly as indicated by the arrow through theannular space be -brazed to the platinum tube 12 sealed in the outer endof the glass cathode stem E making vacuum tight joints. 11 is a metallictube 13, spaced at its inner end from the cathode C and having theprojection 14 making electrical connection with the cathode C or thetube 11. The other end of the tube 13 is soldered or otherwise connectedto the metallic ferrule 14, making an air tight joint therewith-,theferrule 14 being secured upon the end of the outer tube or sleeve 15 ofglass or any other suitable material. Electrical connection is made fromthe negative terminal of the aforel mentioned source of current With theterrule .14 or the tube 13 which communicates electrically with thecathode C. rl`he sleeve or tube 15 is supported upon the glass cathode,

stem' E by the member 16, of'cork or other suitable material, which hasa plurality ot longitudinallyY extending grooves 17 forming airpassages. c

rlhe tube or sleeve 15 preferably terminates in the bell 18 whichextends around v the bulb B to any suitable distance.

Air or other cooling medium is introduced into the tube 13, passestherethrough and strikes the cathode C, cooling the same, and thenpasses outwardly in the annular space between tubes 11 and 13 into thesleevel or tube l5 thence through the passages 17 over the outside ofthe cathode stem E into the bell 18 from which it issues over the outersurface of the bulbB, all as indicated by the arrows; or in the reversedirection if tube 13 is connected to a 'suction pump or a partialvacuum. And We have found'/ that thev air or other vmedium issuing fromthe bell 18 clings or remains close to the bulb -B even beyond itsmiddle or equator.`

Sealed to the bulb B is av tube 19 whose interior space 20 is incommunication with f Within the tube gaarne? the interior of the bulb B.Supported by the tabel@ is the glass bulb or vessel 21 into whichprojects tneftube 22 of platinum,

pailadinmv or any other suitable metal or material which is capable ofoperation as an osmotic member or membrane. rlhe tree end ot thextube 22is closed and its other end is sealed in the glass and its open endcounicates with the' space 20. A conductor 23 connects at its one endwith the tube 22 and at its other en d With-the platinum or other t wire.2t-sealed through the wall of the bulb A' second! platinum or othersuitable wire 25 is sealed in the glass wall of the l bulb. 21 and `isconnected by conductor 23 v with the osmotic tube 22.

It will be noted that the bulb 21 is completely sealed against the-outeratmosphere yand is s ealed against the interior space 2O communicatingwith the interior of the X-rayv tube B -by the osmotic member 22. lnthey bulb21 is sealed an isolated charge of regulating gas for admissioninto the vacuum of the vbulb B through the tube 22. The gas so sealed.in ythe bulb 21 may be at atmospheric-pressure when the regulator ismade,y

or may be Vabove or below atmospheric pressure, but -in any case it ispreferably at a pressure high as compared withy the ,pressure within.the bulb B. The amount of gas or gases sealed in the bulb 21 issujlicient for a great number of regulations 'of the vacuum in the bulbB, because of the very great amount of regulating gas in the bulb 21 ascompared with the amount in 'the bulb lB ,at anytime.

` The gas in the bulb 21 is lpreferably'hydrogen, though it is to beunderstood that anyv other suitable gas or mixture of gases.

may be employed. For example, the monatomic gases, such as argon,helium, neon, zenon, etc., may be employed either singly or incombination, or in combination with hydrogen or other gas or gases.

A. second osmotlc tube or member 28 is sealed in the glass and has itsopen end in communication with the space 20, While its outer closed endis Within the bulb 29, which is open to the atmosphere at 30, or whichmay be closed or sealed and contain a gas or mixture of gases in whichthere is no gas of the character to be transferred from- Within the bulbB through the tube 28 into the bulb 29 for raising the Vacuum, or, moregenerally speaking, in which the con'- centration of the gas of thecharacter to be removed from the bulb Bis less than it is at any timewithin the bulb B. A conductor 31 connects at its one end to the osmotictube 28 and at itsother end to the platinumor other wire 32 sealed inthe wall of thefbulb 29. A conductor 33 connects at its one end to thetube 28 and at its other end to the platinum or other Wire 34 sealedthrough the wall of the bulb 29.A

When it is desired to lower the vacuum within the bulb B, that is, raisethe gas pressure therein, the tube 22 of the lowering regulator isheated by passing an electric current therethrough as from conductors 24and 23, thence through the tube 22, and thence through conductors 26.and 25. The tube 22 being so heated, hydrogen or other regulating gaswill pass by osmosis through bulb 21 through the wall of the. tube 22 tothe interior of the tube 22, .thence to the space 20 and thence into thebulb B, lowering the vacuum, the pressure of the hydrogen or other gaswithin the bulb B being slight indeed as compared with the pressurewithin the bulb 21.

If on the other hand it is desired to raise the vacuum of the bulb B,that is, to take hydrogen or other gas out of the bulb B, current ispassed through the conductors 32 and 31 thencethrough the raisingregulator tube 28 and thence through conductors 33 and 3ft to heat thetube 28, and there being substantially no hydrogen 'or other gas of thebulb B in the air or within the bulb 29 the hydrogen or other gas willcome out of the bulb B by osmotic action through the tube 28 and throughits wall into the bulb I 29, notwithstanding the fact that the gaspressure'in the bulb 29 is very many times higher than the gas pressurewithin the bulb B.

By preference, particularly when hydrogen is used as the regulating gas,and particularly when the gas within the bulb 21 is entirely orl largelyhydrogen, we make the osmotic tube 22 of platinum and the osmotic vtube28 of the raising regulator of palladium. That is, in the loweringregulator, under the circumstances described, we prefer to use a.material forv the tube 22 through which the gas does not so readily passby osmotic action, while the tube 28 is preferably made of a materialthrough which the. gas will very'readily pass by osmotic action.

However, in the lowering regulator the osmotic member 22 may be made ofpalladium or other suitable material which passes through its wallhydrogen or other regulating gas when above a certain concentration andat ordinary temperatures. In such case we prefer to reduce theconcentration of the hydrogen or other regulating gas so that when thetube 22, is at ordinary temperature it will not pass hydrogen or otherregulating gas. To this end the hydrogen or other regulating gas,`whether confined or sealed in the bulb 21 or whether supplied from anexternal source, is diluted by admixture with some other gas which will-not at all or with very great diiiiculty pass through they osmoticmaterial 22 when at ordinary teminverted or delivered to the outer wallof the tube 22 may be a mixture of 'substantially ten per cent. hydrogenand ninety per cent. nitrogen, and, the tube 22 being of palladium, forexample, little or no hydrogen of such -concentration will pass throughits wall at ycially when confined, should be such as to be'non-explosive lor non-combustible wheny raised to the temperature towhich the tube 22 is raised either `by current conducted through thetube 22 as above described, o1" when using a spark gap to heat the same,as described in our said prior application and r in connection withFigs. 5 and 6 herein.

In Fig. 3 G is a source of alternating current, for example, a motorgenerator or rotary, supplying current through the reversing switch Sand adjustable resistance 'R tothe primary 79 of the transformer Thaving the high potential secondary s delivering current through thesynto the positive and negative high ytension vconductors P and Nconnected respectively to the anode A and cathode C of the X-ray tube.One'termin al of the low tension Valternating current circuit isconnected by conductor 541 with one terminal of each of the transformerprimaries 791 and 792 whoseothcr terminals connect respectively with oneterminal of the resistance r1 and r2 adapted to be swept over or engagedby the manually or otherwise operated switch arm 55 connected to theother conductor 56 of the low tension alternating current circuit.Associated with the primaries 791 and 792 are the secondaries s1 and s2,in whose respective circuits are included the lowering and raisingosmotic tubes 22 and 28. Since these tubes 22 and 28 communicatewith/the interior of the X-ray tube, during operation of the ,X-raytube' these regulator tubes assume high potentials, and consequentlybetween the primaries 791 and 792 and their secondaries sland s2 isprovided high potential insulation 57.

By this arrangement the X-ray tube may be kept in operation by energydelivered by the high tension conductors P and N and while in operationthe vacuum may be lowered by bringing theswitch arm 55 into engagementwith resistance r1, whereupon the secondary s1 will pass current throughthe e@ ing resistance to convert the electrical-enas a storage or otherbattery or generator of direct current, or the secondary of atransformer for delivering alternating current. The source 35 is'connected in circuit with the adjustable resistance v36- and' the doublethrow switch 37. When the source 35 delivers alternating or fluctuatingcurrent the member 36 may be a resistance or a re-v actance orimpedance. When the switch 37 is thrown over to the right it connectswith contacts 38 and 39 connected respectively by conductors 40 and 41with the wires 24 and 25, thus conducting current through the osmoticmember 22 to heat the same, the temperature being determined by thecurrent strength which is in turn determined by the adjustableresistance 36. For heating the osmotic member 28 the switch 37 is thrownover to the left in engagement with contacts 42 and 43 communicatmg,respectively, through conductors 44 and 45 with the conductors 32 and 34to transmit current through the tube 28 whose temperature again isdependent upon a current strength which is agaln determined by theadjustable resistance 36.

Where thev osmotic member is heated as above described, it itselfoperates as a heatergy into heat whose 4amount is determined by thesquare of the current multiplied by the resistance of that .part of theosmotic member through which the current flows..

1n F ig. 5 is shown a regulator comprising a single osmotic member 22ato be utilized for eitherrraising or lowering the vacuum with which thespace 20 is in communication. The tube 22a consists of palladium, thoughother suitable material may be employed. 1n a bell or bulb 29a, open tothe atmosphere i at 29", is a cork or `other member a through whichextends the glass or other tube b in whose outer end is a cork or otherstopper member c through which extends the wire or conductor alterminating in the space e between the member c and the wall f ofporcelain or other porous material through which extends the platinum orother conductor g, the tube 22a`extending into the mouth of the bottleor tube b and separated by `a gap from the conductor g. The tube 22a isconnected by conductor 23 to the wire 24*il which may be sealed throughthe wall of the member retaper 29a. The wire 25a may be sealed throughthe wall of the member 29a and terminate in a button 26a separated by aspark gap f from the tube 22a.

1n the space e within the bottle or tube b may be placed water, alcohol,oil, such as mineral oil, or any other suitable hydrocarbon or source ofhydrogen or other gas required. c

lW hen it is desired to lower the Vacuum of the' main bulb or X-ray tubecurrent is passed from the positive conductor d through the water orelectrolyte in the space e to the conductor g andthence across the .i

gap to the tube 22a which is preferably a cathode or negative terminal.The passage of the electric energy through the material other materialwill be carried through member f by electrostatic action, and thendecomposed into hydrogen or othergas which then passes through theheated wall of the tube 22a into the main bulb or X-ray tube to lowerthe vacuum.

rl`he same tube 22a may be used for raising the vacuum, by connectingthe Wire 25a with the positive conductor of the circuit and ycausingthe'current to leap the gap to the cathode 22a heating the same,whereupon hydrogen or other gas will pass out of the main bulb or X-raytube through the wall of the tube 22a which is surrounded byair, andoperation being the same as hereinbefore described.

In Fig. 6 there extends through the cork or other stopper a member L, ofporcelain or other porous substantially nonfconducting material. Themember h may be hollowed out at its inner end as shown to re ceive theend of thetube 22a. And the positive` conductor d may be connected tothe member 'it in any suitable way, as by wrapping the same around themember la several times. The pores of the member k are charged with anoil or hydrocarbon or other suitable material, as described inconnection with Fig. 5. A y

0n passage of current from the conductor d to the tube 22V which isconnected to the negative side of the circuit by -wire 24agas will beliberated and collect within the hollow end of the member L around theendv of tube 22a which is heated by the spark or arc with the resultthat the gas will pass through passing current from the wire 25a acrossthe gap to the tube 22a, which is surrounded by air, with resultantraising of the vacuum as hereinbefore described.

It will vbe understood that the structure of eitherFig. 5 or Fig. 6 maybe Aused in place of the two regulators in any of the arrangementshereinbefore described and for both automatic and manual regulation.

While the structures of Figs. 5 and 6 above described are suited for theemployment of current of suicient tension to jump across gaps, it willbe understood that the osmotic members 22a may be heated by conductionas illustrated in Figs. 1 to 4 inclusive, or by radiation as in Fig. 7,by using low tension current. 25a may be connected directly to themembers 22a without an intervening spark gap, in which case thearrangement will be the same as that indicated in the previous figures.And with such connection of the members 25a directly to the members 22athe gas may be produced by use of higher tension current by utilizingthe same structures illustrated in Figs. 5 and 6 for this purpose. Orthe gas may be evolved by suitably heating the gas'producing materialelectrically as by the same current which heats the members 22a, or by aseparate current.

In Fig. 7 22 represents an osmotic member for use in any relationincluding the relations hereinbefore described. To heat the member 22 itis surrounded by the resistance coil 46, preferably spaced from themember 22 to allow presence of regulating gas. The coil 26 is preferablyembedded in refractory non-conducting material 47. The coil 46 isconnected in a circuit with any suitable source of current, as 48; andthe strength of the current in the circuit may be regulated by theadjustable resistance 49. To heat the member 22 the circuit is closed bvclosing switch 50 and the resistance 49 adjusted until the desiredtemperature is reached, the heat transfer from the coil 46 to the member22 being by either radiation or conduction, or both.

The tube 22 may have its closed end external to the vacuum as in Figs.1, 2, 4, 5 and 6 with the heating coil 46 also external to the vacuum.Or the open end yof tube 22 may be external to the vacuum andthe closedend and coil 46 within the vacuum.

Where there is in the bulbs 21 a vacuum regulating or other gas whichwould form a. combustible or explosive mixture with air which might leakinto the bulbs 21 because of cracking or which might otherwise bepresent, any suitable vmaterial may be placed within the bulbs 21 toreact with the funvwhose number of turns is adjustable.

Thus the conductors desired gas or gases to prevent forming acombustible or explosive mixture.

Such material is represented at Ph,`Fig. 4, and may be a piece ofphosphorus,prefer ably adhering to the wall of the bulb 21 to preventits displacement wher'rthe X-ray -tube and the regulators are lmovedabout. Phosphorus is particularly useful when hydrogen is used becauseit will immediately combine with the oxygen lof any entering air andthus prevent formation of an explosive or combustible mixtureof hydrogenand oxygen. v v

In Fig. 8 the conductors 54 and 56 supply low tension alternatingcurrent to the transformer T, R being an adjustablel re.- sistance. inthe circuit of the primary p The high potential secondary s deliversuni-directional high tension current through the rectifying switch F, asin Fig. 3, to the positive and negative conductors P andl N.

The anti-cathode A is connected to yan osmotic member 22, of either avacuum lowering or raising regulator, and to a spark gap terminal 58.The associated sparkgap terminal 59 connects through conductor P to therectifying switch F. Disposed near the tube 22 is the spark gap terminal60, the tube 22 and terminal 60 forming a spark gap whose terminals areconnected in parallel with the spark gap terminals 58 and 59. Disposednear the' spark gap .terminals 58 and 59 is the con-ducting member 61supported upon the end of the insulating member 62 carried bythearmature 63 of electromagnet 64 and pivoted at 65.V A spring 66, undertension, connects at its one end to the armature 63 and at its other endto the adjusting screw 67 which adjusts the tension of the spring 66.The electro-magnet 64 has its one terminal connected to the conductor 54and its other terminal to the adjust-f the circuit of the electro-magnet64 1s 1n shunt to a'part of the primary p. Associated with the movablecontact 69`is the scale 71 reading in units corresponding with differentdegrees vof vacuum of the X-ray tube.

Assuming the osmotic-tube 22 to be part of a vacuum lowering regulator,and the vacuum to be too high, the fall of potential across the primaryp will. be high, especially if the magnetic leakage of the transformer Tis low, with resultant greater current flow through the electro-magnet64, with a given setting of the contact 69. Accordingly theelectro-magnet .64 will at tract its armature 63 in opposition to thespring 66 and remove the member 61 from cthe terminals 58 and 59,thereby producing a spark gap or increasing the length of a spark gap,with the result that the energy passed between the tube electrodes A andC will leap the gap between terminals 60 and tube 22 to heat the latterand cause a lowering of the vacuum as hereinbefore described. As thevacuum is lowered the fall of potential across the X-ray tube willdiminish, as will also the fall ofpotential across the primary p, andaccordingly the strength of current through the electro-magnet 64 willdiminish and the spring 66 will withdraw the .armature 63 and shortenthe spark gap at 58, 59 and 61 so that the energy through the X-ray tubewill no longer jump the gap between 60 and 62, but will pass fromcontact 59 to contact 58 through member 61, with the result that thetube 22 will cool and the vacuum will be no further low ered.

When the tube 22 -1 is that of a vacuum lowering regulator the movementof the contact'69 toward the right, therebycutting out some ofresistance 68, will insure the automatic maintainence of a low vacuum.,while movement to the left will insure automatic maintainence of ahigher vacuum.

In this arrangement of Fig. 8, therefore, there is a spark gap forcontrolling a vacuum regulator, which spark gap is in series wlth theX-ray tube proper; and this regulator spark gap is shunted by anotherspark gap whose length is automatically varied in response-to degree ofvacuum of the X-ray tube.

In Fig. 9 the arrangement in the primary circuit is similar to that inFig. 8 except that the electro-magnet now takes the forni of a solenoid72 whose core 73 is attached to the insulating lever 62 pivoted at 65and controlled by spring 66 which is in turn adjustable by. .the screw617.

The X-ray tube is here shown as provided with both a vacuum loweringregula-tor and a vacuum raising regulator, the former comprising theosmotic tube 22 and spark gap terminal 60 and the latter comprisingr theosmotic tube 28 and the spark gap terminal 74 connected through positiveconductor P to one terminal of the rectifying switch F.

The tube 28 is connected to the spark gap terminal 60 and to theconductor75. 'lhe tube 22 is connected to the anode of the'X- ray tubeand to the conductor 76, and the spark gap terminal 74 is connected tothe conductor 77. rlihese conductors 75, 76 and 77 are disposed adjacenteach other 'but at such distance from each other that sparking does notoccur between them. Movable across and near the conductors 75, 76 and 77is the conducting member 61 carried by the lever 62. rlhe `arrangementotthe conductor 61 and the conductors 75, 76 and 77 is shown in Fig. 9a. v

- Here again the solenoid 72 becomes more mesma? weakens as the vacuumlowers.

As the vacuum rises the lever 62 will be. drawn to the left-by thesolenoid 72 until the member (i1 passes/beyond the conductor 76 andbridges only conductors 75 and 77, whereupon the current vis passed fromthe high tension switch l" through the conductor P to conductor 77 toconductor 61 to conductor 75 and to spark gap terminal 60, and thenceacross the gap to the tube 22 and thence to the X-ray tube. This heatsthe tube 22 with resultant lowering of the lf the vacuum becomes too lowthe spring 66 will draw the member 62 to the right until the member 61passes beyond the right end of conductor 77, whereupon current will passfrom conductor P to spark gap terminal 74 and thence acrossthe gap tothe tube 28 and thence. to conductor 75, to conductor 61, to conductor76 and thence through the X-ray tube. Accordingly the tube 28 is heatedand the-vacuum raised..

The setting of the contact 69 will cause the apparatus to automaticallymaintain a vacuum between certain upper and lower limits, which limitswill vary withv adjustment of the contact 69. l

lin Fig. 10the automatic regulation is procured in response tofluctuations in potential of the high tension circuit across the anodeand cathode of the X-ray tube. .This method of regulation isthereforeyavailable whether or not the high tension transformer 'll` hassmall magnetic leakage.

The high tension positive and negative conductors P and N connect withthe anode and cathode respectively as described. However, in one ofthese conductorsfas P, there is a spark gap between the stationaryterminal 78 and the adjustable terminal 79, the energy passed throughthe Xray tube passing over the gap between these terminals. In this casethe current for heating the regulator tubes 22 and 28 passes over thespark gaps. Connection for this purpose is made from positive conductorF to the conducting member 80 pivoted at 8l and controlled by thetorsion spring 82 whose free end carries a pointer 83 which may beclamped in any desired position with respect to the scale 84, similar tothe scale 68 in Fig. 8, as by fricstrongly energized as the vacuum risesand 65 Ation between the scale and pointer. The

lill@ opposite end of the beam 8O is an adjustable counter-weight 93 forbalancing the beam so that its normal position shall be indicated.

In normal operation the high potential energy will leap across the gapbetween terminals 78 and 79 and pass through the X-ray tube to energizethe same. This spark gap length is less than the sum of the lengths ofthe spark gaps between 86 and 88 and 88 and 28, aiidlessthan the sum oflthe lengths of the spark gaps between 85 and 87 and -87 and 22, withthe result that normallycno current will pass over these regulator sparkgaps. Under normal conditions the electrostatic charges on arcs 90 and91, being of similar sign, cause these arcs to repel each other,y andthis repulsive force coperating with the counterweight '93 and thespring 82 maintain the beam 8O balanced as shown. If however the vacuumof the X-ray tube should raise. the potential across the `X-ray tubeterminals will increase and the potential of the arcs 90 and 91 will behigher and they will repel each other with greater force, tilting thebeam 80 in a clockwise direction about its pivot 81 bringing theterminal 85 closer and closer tothe conductor 87 so that eventually thespark gap at these regulator terminals is shorter than the spark gapbetween the terminals 78 and 79 whereupon the current will pass throughthe regulator spark gaps atthe right heating the lowering regulator tube22 causing the vacuum to be automatically lowered.

And if the vacuum has raised to a great eX tent the unbalancing of thebeam 80l will be so great as to bring contact 85 into engagement withcontact 87, which latter then acts as a stop for the beam. v

On the other hand if the vacuum of the tube is too low it will beautomatically raised because of the decrease of potential of the arcs 90and 91 allowing the beam 8O to move in a counterclockwise direction onits pivot 81 to shorten-the gap at the terminal 88, thereby causing thecurrentto pass across the spark gap between 86 Vand 88 to heat theraising regulator tube 28, causing theV ali/to"- matic raising of thevacuum. By adjusting the screw` contacts 79, 85 and 86 the amount ofVariation of vacuum to either side of that indicated by the scale 84 maybe adjusted.

If the connection 92 between the arcs 90 and 91 is omitted and when insuch case the ai'c 90 remains as indicated in the drawing or isconnected to the positive conductor P, in such latter case substantialinsulation intervening between arcs 90 and 91. the arcs '90 and 91 willcarry charges of opposite signs and twill therefore attract each other.And this attractive force will var v with the potential differenceacross the X-ray tube terminals and therefore with the degree of Vacuum.Withfalling vacuum the attrae' tion between the arcs 90 and'91 willbecome less and the beam 80 will thenmove 1n a clockwise direction aboutits pivot 81. Accordingly vfor this arrangement the arcs 90 and 91 andthe counterweight 93 should be interchangcd asto their positions withrespect to the beam 80, orthe spark gaps for the regulator tubes shouldbe interchanged.

It will be understood also that in place of l osmotic regulatorsdescribed in connection with Fig. 10 the ordinary gas evolvingregulators maybe used in association with the spark gaps described, theenergy passed over these gaps serving to liberate the vacuum regulatinggas. f

-It will be understood that While osmotic' regulators have beendescribed in connection with Figs. 8,` 9 and 10, that any other type ofregulator may be used, as for example, the ordinary regulators involvingmaterial which upon being `heated will evolve gas within the vacuum,-the spark gaps of these figures being used to pass energy to` suchordinarv regulators. In Fig. 11 the osmotic tube, 'as 22,' is shown witha thickened end 22e which may be used as the terminal of the spark gap,

such thickened end 22e withstanding greater 1 l heat than the thinnerparts or walls of the tube 22. The` thickened end of the tube 22 may beproduced in any suitable way, as forV example. by fusing the closed endof the tube 22 until it thickens, as illustrated.

f It will be understood that the osmotic members or membraneshereinbefore de- .scribedmay take other`than the tubular freely thanplatinum. By alloying platinum and palladium. however, there results anosmotic material which passes hydrogen with less facility than palladiumalone. Such alloys may with advantage be used with different partialpressures of the reguice lating gas or gases and with different degrecsof dilution of the regulating gas or gases. #7 i lVhile the air coolingof ,the X-ray tube hereinbefore described is of advantage, it will beunderstood that our invention is not limited to the use of our hereinclaimed exterior of said wall exposed to the atmos-4 claim in ourlapplication Serial Number' .195,009, filed October 6, 1917,certainsubject matter not herein claimed.

What we.claim is:

1. Means for regulating the vacuum of a vacuum tube comprising anosmotic memberforminga wall of said tube, dierent gases external to saidtube in contact with said osmotic `member, said member when heatedadapted to allow passage therethro-ugh of one or more of said' gases andto exclude another orothers of said gases, and

means for electrically heating said member including a spark gap inproximity' to'saidi member.

2. A'ragulatoil for the vacuum of a vacu-f um tube comprising anosmoticmember, amass of porous material charged with gas`- evolvingmaterial disposed in proximity` to 'said member, andelectrical,connectionsl to 'said member and said porou's material.

3. A regulator for the vacuum of a vacu- 1 um tube comprising an osmoticmember, a mass of porous material charged with gas evolving materialdisposed in proximity pito.- said member, electrical connections to saidi member and said porous material, and a` spark gap terminal spacedfromsaid member.

l. A regulator for the vacuum of a vacuum tube comprising an osmoticmember, a container for electrolyte, said container having a porouswall, electrical connection into said container, a conductor extendingthrough said porous wall and spaced from said member. 4

5. A regulator for the vacuum of a vacuum tube comprisingv an osmoticmember, a container for gas evolving material, said container having aporous Wall, .and a conductor extending through said container and aidporous wall and spaced from said meiner. v

6. The combination with a vacuum tube, of a regulator for raising andlowering the vacuum of said tube comprising an osmotic member forming awall of said tube, gas evolving material. means for subjecting saidmaterial to the eiiects of-an electric current to cause evolution -ofgas, means forelectrically heating said osmotic member for allowingpassage of the evolved gas therethrough, and means for electricallyheating said member without evolution of gas for passageof gas from saidvacuum tube to the exterior of said osmotic member.

7. A regulator for the vacuum of a vacuuml tube comprising an osmoticmember forming a wall of said tube, a portion of the phere, means forsupplying regulating, gas

in connection with an air cooled werpen to another portion of theexterior ofvsaid member, and means for heatin said inember for causingpassage of gas t erethrough to or from the interior of said tube.

8. A regulator for the vacuum of a vacuum tube comprising an osmoticmember `forming a wall thereof, gas evolving material in proximity tosaid member, a conductor disposed in proximity to said member, andImeans for passing current through said conductor and said gas evolvingmaterial.

9. An osmotic'member or membrane having althin gas passing portion andan integral -massive portion. n

10. An osmotic member having integral thin and massive portions,`andmeans for 30 raising the temperature of said massive portion'. wherebyheat is conducted to said thin portion. y v l ,11. An osmotic membercomprising integral thin and massive portions, said massive portionforminga terminal of a spark gap.

12. The combination with an X-ray tube, tof a spark gap in seriestherewith, a v acuum regulator comprisingpa spark gap in parallel withsaid first named spark gap, and

means for' altering thel length of ,one of' said ga s.

13. '1 e combination with an X-ray tube, of a spark gap in seriestherewith, a vacuum regulator comprising a spark ap in parallel withsaid first named spar gap,4 and means responsive to change in degree ofvacuum 'of said X-ray tube for altering the length of one of said sparkgaps.

14. The combination with an X-ray tube, 10( of a spark gap in seriestherewith, a vacuum regulator comprising a spark gap in parallel withsaid first named sparky gap, a movable member adapted to change thelength of one of said spark gaps, and electro-magnetic means controllingsaid member.

15. The combination withv an X-ray tube, of a spark gap in seriestherewith, a vacuum regulator comprising a sparkY gap in parallel withsaid rst named spark gap,a movable member adapted to change the lengthof one of said spark gaps, and electro-magnetic means responsive tochanges in degree of vacuum of said X-ray tube conv trollin said member.115

16. y he combination withl an X-ray tube, of a spark gap in seriestherewith, a vacuum regulator comprising a spark gap in parallel withsaid first named spark gap, a movable member adapted to change thelength of one of said spark gaps, a step-up transformer supplying saidX-ray tube, and electromagnetic means connected in the primary circuitof saidv transformer controlling said member.

17. rllhe combination with an X-ray tube, of a spark gap in seriestherewith, a vacuum regulator comprising a spark ygap in paraliia lelwith said first named s ark gap, a movable member adapted to change thelength of one of said spark gaps, a step-up transformer supplying saidX-ray tube, and electro-magnetic means connected in parallel with theprimary winding of said transformer controlling said member.

18. The combination with an X-ray tube, of a spark gap in seriestherewith, a vacuum regulator comprising a spark gap in parallel withsaid first named spark gap, a movable member adapted to change thelength of one of said spark gaps, a step-up transformer supplying saidX-ray tube, and electro-magnetic means connected in parallel with a partof the primary of said transformer controlling `said member.

19. The combination with an X-ray tube, of a spark gap in seriestherewith, a vacuum regulator having a spark gap, said spark gapconnected in parallel with each other, and means for varying the lengthof said first named spark gap.

20. The combination with an X-ray tube, of a spark gap in seriestherewith, a vacuum regulator havin a spark gap, said spark gapsconnected 1n parallel with each other, and means responsive to thevariations in the vacuum of said X-ray tubevfor varying the length of.said first named spark gap.

21. The combination with an X-ray tube, of a spark gap in seriestherewith, a vacuum regulator having a spark gap, said spark gapsconnected in parallel with each other, and means for varying the lengthof said regulator spark gap.

22. The combination with an X-ray tube, of a spark gap in seriestherewith, a vacuum regulator having a spark gap, said spark gapsconnected in parallel with each other, and means responsive to thevariations in the vacuum of said X-ray tube for varying the length ofsaid regulator spark gaps.

23. The combination with an X-ray tube, of vacuum raising and lowerinregulators comprising spark gaps, means or shunting said spark gaps, andmeans responsive to changes in degree of vacuum of said X-ray tubecontrolling said means.

24. ,The combination with an X-ray tube, of vacuum raising and lowerinregulators comprising spark gaps, means or shunting said spark gaps, andelectro-magnetic means responsive to changes in degree of vacuum of saidX-ray tube controlling said means.

25. The combination with an X-ray tube,

' of vacuum raising and lowering regulators,

a spark gap for each of said regulators, a spark gap in parallel witheach of said spark gaps, and means for varym the length of a spark gapof each pair o parallel connecting spark gaps.

26. The combination with an X-ray tube, of vacuum raising and loweringregulators,

a spark gap for each of said regulators, a spark gap 1n series with saidtube and in paralle with each of said spark gaps, and means for varyingthe `length. of a spark gap of each pair of parallel connected sparkgaps- 27. The combination with an X-ray tube, of vacuum raising andlowering regulators, a spark gap for each of said regulators, a spar-kgap in parallel with each of said spark gaps, and means responsivertovariatlons 1n degree of vacuum of said X-ray tube for varying the lengthof a spark ga of each pair of parallel connected spar gaps.

28. The combination with an X-ray tube, of vacuum raising and loweringre ators, a spark gap for 'each of said regu ators, a spark gap inparallel with each of said spark. gaps, and electro-magnetic meansresponslve to variations in degree of vacuum of said X-ray tube forvarying the length of a spark gap of each pair of parallel connectedspark gaps.'-

29. The combination with a vacuum tube, of a vacuum lowering and raisingregulator,l a scale having marklngs corresponding with degrees of vacuuman index associated with said scale, means for controlling saidregulator including electro-magnetic means, and means determining theoperation of said controlling means set with said index.

30. The combination with a vacuum tube, of a scale having markingscorrespondin with degrees of vacuum, an index associate with said scale,a vacuum regulator, and means for controlling said regulator comprisingelectro-magnetic means and means set by movement of said index.

' 31.- The combination with a vacuum tube, of a vacuum regulator, ascale having markings corresponding with degrees of vacuum, an indexassociated with said scale, means for controlling said regulatorincluding electro-magnetic means, and current-regulating meansdetermining the operation of said controlling means set with said index.

32. The combination with a vacuum tube, of a scale having markingscorresponding with de ees of vacuum, an index associated with sa1dscale, a transformer for exciting said vacuum tube, a vacuum regulator,means in shunt with the primary of said transformer for controlling saidregulator, said means comprising an electro-magnet andcurrent-regulating means set with said index.

33. The combination with a vacuum tube, of a scale having markingscorrespondin with degrees of vacuum, an index associated with saidscale, a transformer for exciting said vacuum tube, said transformerhaving low magnetic leakage, a vacuum regulator. means in shunt with theprimary of said transformer for controlling said regulator, said meanscomprising electro-magnetic means and current-regulating means, saidcurrent regulating means being set with said index.

34. The combination with a vacuum tube, of a vacuum regulator, latransformer for exciting said vacuum tube, said transformer having lowmagnetic leakage, means in shunt with the primary of said transformerfor controlling said regulator, said means comprising electro-magneticmeans and current-regulating means.

35. The combination With a v acuum tube,

of a vacuum regulator comprlsing an osmotic member a transformer forexciting said tube and supplyingcurrent to said regulator, saidtransformer having low magnetic leakage, and electro-magnetic means in20 electrical connection With the primary of mamar said transformer forcontrolling said regulator. A

36. The combination with a Vacuum tube, of a Vacuum regulator comprisingan osmotic member, a transformer for exciting said tube andsupplyingcurrent to said regulator, and electro-magnetic means in electricalconnection With the primary of said transformer for controlling saidregulator.

37. ln a vacuum regulator, an osmotic member of material containingplatinum and palladiuml 38. In a vacuum regulator, an osmotic membercomposed of an alloy of platinum and palladium.

In testimony whereof We have hereunto ailiXed our signatures this 10thday of June,

HOMER CLYDE SNOOK. EDWIN W. KELLY.

